Information-related devices and methods

ABSTRACT

A product has a surface provided with a first coding pattern and a second coding pattern. The coding patterns may include symbols each of which represents at least two different values. Each symbol in the first coding pattern may be defined by one raster point and at least one marking, the raster point being included in a first raster, which extends over the surface. Each symbol in the second coding pattern may also be defined by one raster point and at least one marking, the raster point being included in a second raster. This second raster may be displaced in relation to the first raster and may have a different spatial scale than the first raster. Each symbol in the first and the second pattern may have a value which, for example, can be indicated by the location of the marking belonging to the symbol in relation to a raster point in the first and second raster, respectively.

Cross-Reference to Related Applications

[0001] This application claims priority benefits based on Swedish PatentApplication No. 0001235-1, filed Apr. 5, 2000, and U.S. ProvisionalApplication 60/210,647, filed Jun. 9, 2000, the technical disclosures ofboth of which are hereby incorporated herein by reference.

FIELD OF THE INVENTION

[0002] The present invention relates to an apparatus and method fordetermining a position on a surface containing a coding pattern.

BACKGROUND OF THE INVENTION

[0003] In many situations it is desirable to determine an absoluteposition on a surface. For example, it may be desirable to determine aposition on a surface when recording and digitizing a document such as adrawing or map. It may also be desirable to determine a position of asurface when creating an electronic version of handwritten information.

[0004] In these and other situations where position-determination iscarried out, it is often desirable to have a computer program, incooperation with an input device, carry out position-determinationcalculation and, in particular, to read and process position informationand other information that, for example, can be related to the absolutepositions read and determined.

[0005] U.S. Pat. No. 5,852,434 describes a device for determining anabsolute position. The device comprises a writing surface, which has aposition-coding pattern for determining X-Y coordinates, a detector,which can detect the position-coding pattern, and a processor, which candetermine the position of the detector in relation to the writingsurface based on the detected position-coding pattern. The device allowsa user to input handwritten or hand-drawn information to a computer atthe same time the information is written or drawn on the writingsurface.

[0006] Generally, the smaller the symbols are, the more difficult it isto produce the patterned writing surface and the greater the risk ofincorrect position determinations. On the other hand, the larger thesymbols are, the worse the position resolution.

SUMMARY OF A FEW ASPECTS OF THE INVENTION

[0007] In accordance with the invention, there may be provided a surfacecomprising a first coding pattern of symbols and a second coding patternof symbols wherein each symbol of the first coding pattern has at leasttwo different values and each symbol of the second coding pattern has atleast two different values. Each symbol of the first coding pattern maybe defined by a first raster point and at least one first marking,wherein the first raster point is included in a first raster, whichextends over the surface. Each symbol of the second coding pattern maybe defined by a second raster point and at least one second marking,wherein the second raster point is included in a second raster which isdisplaced in relation to the first raster and has a different spatialscale than the first raster.

[0008] There may also be provided, a device for reading aposition-coding pattern and an information-coding pattern on a surface,wherein the position-coding pattern and the information-coding patterninclude symbols which each represent at least two different values,wherein the values depend on position information and other informationfor the position-coding pattern and the information-coding pattern,respectively. The device may include means for reading a part of thesurface and storing the information read in an image, means fordetermining a first virtual raster with first raster points in the imageassociated with the position-coding pattern and a second virtual rasterwith second raster points in the image associated with theinformation-coding pattern. The second raster may be displaced inrelation to the first raster and may have spatial scale other than thatof the first raster. The device may also include means for locating aplurality of symbols in the position-coding pattern and theinformation-coding pattern and means for determining the value of eachof said plurality of symbols. Each symbol in the position-coding patterna first raster point in the first raster and at least one first markingand each symbol in the information-coding pattern may include a secondraster point in the second raster and at least one second marking.Further, the device may include means for separating the position-codingpattern in the image into a first position code for a first coordinatefor the partial surface and a second position code for a secondcoordinate for the partial surface by translating the value of eachsymbol into at least one first digit for the first position code and atleast a second digit for the second position code. Still further, thedevice may include means for calculating the first coordinate based onthe first position code and the second coordinate based on the secondposition code.

[0009] Further, there may also be provided a method for producing aposition-coding pattern and an information-coding pattern on a surface,wherein the coding patterns comprise symbols, which each represents atleast two different values. The values may depend on positioninformation and other information for the position-coding pattern andthe information-coding pattern, respectively. The method may alsoinclude determining a first raster with first raster points and a secondraster with second raster points. The second raster may be displaced inrelation to the first raster and may have a different spatial scale thanthe first raster. The method may also include determining aconfiguration of the symbols of the position-coding pattern and theinformation-coding pattern. Each symbol of the position-coding patternmay be defined by a first raster point in the first raster and at leastone first marking and each symbol in the second coding pattern may bedefined by a second raster point in the second raster and at least onesecond marking.

[0010] The foregoing summarizes only a few aspects of the invention andis not intended to be reflective of the full scope of the invention asclaimed. Additional features and advantages of the invention are setforth in the following description, may be apparent from thedescription, or may be learned by practicing the invention. Moreover,both the foregoing general description and the following detaileddescription are exemplary and explanatory and are intended to providefurther explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The accompanying drawings, which are incorporated in andconstitute a part of this specification, illustrate several embodimentsof the invention and together with the description, serve to explain theprinciples of the invention.

[0012]FIG. 1 shows an embodiment of a product that is provided with aposition-coding pattern in accordance with the present invention.

[0013]FIGS. 2a-2 d show: symbol configurations in an embodiment of thepresent invention.

[0014]FIG. 3 shows an example of 4×4 symbols that may be used for codinga position in accordance with the present invention.

[0015]FIG. 4 shows a device that may be used for reading a codingpattern according to the present invention.

[0016]FIG. 5 shows a position-coding pattern and an information-codingpattern.

[0017]FIG. 6 shows a power spectrum for spatial frequencies of an imagewith two coding patterns.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0018] A first aspect of the invention may include a product which has asurface provided with a first coding pattern and a second codingpattern. The coding patterns may include symbols, which each representat least two different values. Each symbol in the first coding patternmay be defined by a first raster point and at least one first marking,the first raster point being included in a first raster, which extendsover the surface. Each symbol in the second coding pattern may also bedefined by a second raster point and at least one second marking, thesecond raster point being included in a second raster. The second rastermay be displaced in relation to the first raster and may also have adifferent spatial scale than the first raster. In a preferredembodiment, each symbol in the first and the second coding pattern mayhave a value that is indicated by a location of the first and secondmarking of the symbol in relation to the first raster point and thesecond raster point, respectively. Another preferred way of indicatingthe values of the symbols comprises varying the size of the markings asdescribed in Applicant's International Application WO 00/73983, thetechnical disclosure of which is hereby incorporated herein byreference. Moreover, reference is also made to PCT/SE00/01895 and WO01/16691, the technical disclosure of which is hereby incorporatedherein by reference.

[0019] If the displacement between the first and the second raster, thedistance between the raster points in the first raster, and the distancebetween the raster points in the second raster do not have a commondenominator greater than one, unnecessary visual interference effectscan be avoided when printing the pattern.

[0020] The first and second markings that are included in the symbolscan be configured more or less arbitrarily. However, it may bepreferable if the markings are of the simplest possible configuration,for example, round dots as disclosed herein.

[0021] With a coding-patterned product according to the abovedescription, information can be stored on the product in the form ofabsolute-position information and other information of a more or lessarbitrary nature. The different coding patterns can be displaced inrelation to one another by a more or less optional distance and be ofdifferent spatial scales. As a result, the different patterns may notcoincide with one another. A product according to the above description,can have a plurality of different coding patterns, for example three, inwhich the mutual displacements between the patterns should differ fromone another. Such a patterned product may be advantageous in that theinformation density may great and, in practice, only limited by thenature of the surface of the product and the printing technique that isused for the application.

[0022] Examples of other information that is stored in aninformation-coding pattern can be found in Applicant's Swedish PatentApplication 0000947-2, the technical disclosure of which is incorporatedherein by reference.

[0023] It may also advantageous that information is coded in differentpatterns since this may entail simple distinguishing between differenttypes of information such as distinguishing between position informationand other information that can be descriptive of the product to whichthe coding pattern is applied.

[0024] However, in the related art, because each position is typicallycoded with a complex symbol, recognition of many different elements isrequired, which make position coding sensitive to interference.According to the present invention, the value of a symbol is specifiedby the location of a marking in relation to a raster point. Thus, thereis one type of symbol for each value. Therefore, a device that reads,determines positions, and decodes information only needs to detect onemarking and does not need to differentiate between different elements(such as the different lines in a bar code) in order to determine thevalue of the symbols. Detection thus becomes simpler and less sensitiveto interference.

[0025] As mentioned above, in the related art, each position may becoded with a single symbol, which, therefore, must be rather complex.According to the present invention, each position may be coded with aplurality of symbols. Each individual symbol can thus be made lesscomplex and simpler to detect with greater reliability. Furthermore, inthe related art, each position may be coded with a symbol that is“isolated” from the symbols of surrounding positions. This may limit theposition resolution of the surface occupied by the symbol for aposition. The position-coding pattern according to the present inventioncan be made up in corresponding manner where each position is coded byan “isolated” group of symbols. However, in a preferred embodiment ofthe invention, each symbol may contribute to the coding of more than oneposition. In this manner, a “floating” transition between differentpositions may be created. In other words, each position may be codedpartly by the same symbols as the adjoining positions. Floating codingmay be advantageous since it may increase position resolution.Furthermore, it is possible to reduce the relationship between, on theone hand, the number of symbols which a position-determining device mustregister to carry out a position determination reliably and, on theother hand, the number of symbols which code a position.

[0026] In a preferred embodiment, each symbol may contribute to thecoding of both a first and a second position coordinate. Thus, differentsymbols are not necessarily needed for the different coordinates, whichmay make the position code simpler and the position resolution better.The coordinate system can be suitably Cartesian but other types ofcoordinate systems are also conceivable.

[0027] Furthermore, the value of each symbol can be translated into atleast one first digit, which may be used for coding the firstcoordinate, and at least one second digit, which may be used for codingthe second coordinate. The symbols in the position-coding patterntogether may represent a first position code for the first coordinateand a second position code for the second coordinate. The twocoordinates can then be coded independently of one another, which maymake the coding simpler when the coding is “floating”. Preferably, thevalue of a symbol is represented in a binary manner with a first bit forcoding a first coordinate and a second bit for coding a secondcoordinate.

[0028] The position-coding pattern may be based on a first cyclic,preferably binary, number series where no sequence with a firstpredetermined number of digits in the number series appears more thanonce. Because the position-coding pattern may be based on a first cyclicnumber series, it will likely contain inherent information about thepositions so that the coordinates can be calculated according topredetermined rules. This may be advantageous in that the decoding ofthe position-coding pattern can be implemented in an efficient manner insoftware, for example. Besides, it might be much simpler to produce aposition-coding pattern in this way than trying to randomly generate anunambiguous position-coding pattern of a floating type.

[0029] In another embodiment, a product may comprise a plurality ofwriting surfaces, which each comprise a position-coding pattern. Forexample, the product can consist of a notepad with a plurality ofsheets. The position-coding patterns may then differ for the differentwriting surfaces by the sequence in the cyclic number series with whicha predetermined column or row begins. The “same” pattern can thus beused for a plurality of writing surfaces which can be separated from orintegrated with one another by allowing, for example, the first columnto begin in different positions in the number series.

[0030] Although the coding patterns have been discussed above in termsof a separate position-coding pattern and a pattern coding otherinformation, it is possible that both coding patterns encode positioninformation. In such a case the first position-coding pattern may encodepositions from a first region or area and the second position-codingpattern may encode positions from a second region or area. Needless tosay, more than one position coding pattern may also increase the totalsize of the region available for use.

[0031] The position-coding pattern can be implemented with any parameterthat can produce symbols of the above-mentioned type and that can bedetected by a detector. The parameter can be electrical or chemical orof another type. However, the position-coding pattern is preferablyoptically readable which makes it simpler to apply to the surface. Thepattern should thus be able to reflect light, but, the light does notneed to lie within the visible range.

[0032] The raster and/or the raster points can be implemented on thesurface. However, in a preferred embodiment, the raster and the rasterpoints are virtual. Thus, the raster is not marked on the surface atall, but, is an imaginary raster that forms the base of the coding. Theraster can be located from the location of the markings.

[0033] A second aspect of the invention is to produce by means of amethod a position-coding pattern and an information-coding pattern on asurface. The coding patterns may comprise symbols, which each representat least two different values, wherein the values depend on positioninformation and other information for the position-coding pattern andthe information-coding pattern, respectively. The method may includedetermining a first raster with first raster points and a second rasterwith second raster points. The second raster is displaced in relation tothe first raster and may have a different spatial scale than the firstraster. Each symbol in the position-coding pattern may be defined by afirst raster point in the first raster and at least one first marking,and each symbol in the information-coding pattern may be defined by asecond raster point in the second raster and at least one secondmarking. In a preferred embodiment, the configuration of the symbols inthe position-coding pattern and the information-coding pattern may bedetermined by displacing the markings of the symbols, based on the valueof the symbols, in relation to each first raster point and second rasterpoint in the first and second raster, respectively. A computer programcan implement the method.

[0034] Based on a method according to the above description, informationabout absolute positions on the surface of a product can be applied withany other information in a second coding pattern, which is displaced andprovided with a different spatial scale compared with theposition-coding pattern.

[0035] An advantage of the method may be that the different codingpatterns do not have to be applied on the surface of a product on thesame occasion. Instead, the times of applying the different patterns canbe separated and carried out by means of different application devices.For example, a sheet of paper with a background pattern in the form of aposition-coding pattern can be used in a laser printer coupled to apersonal computer that prints an arbitrary number of otherposition-coding patterns with mutually varying displacements betweentheir respective rasters.

[0036] One example of the utilization of a combined position- andinformation-coding pattern can be in the form of blank forms where aposition-coding pattern is printed on a sheet of paper. The sheet ofpaper may be provided by a user with an information-coding pattern andother graphical information such as, for example, a grid pattern,figures etc. where information in the form of, for example, sequences ofdigits that represent data, which is related to the grid pattern or thegraphical figures, is coded with the aid of the symbols in theinformation-coding pattern. When the combined position- andinformation-coding pattern is read, both position-information and thedata that is related to the graphical figures, which are printed on thesheet of paper with the position-coding pattern, may be obtained.

[0037] If both coding patterns encode position information, the firstposition-coding pattern may encode positions from a first region or areaand the second position-coding pattern may encode positions from asecond region or area. When reading symbols from a product provided withsuch a combination of two position-coding patterns, coordinates may besimultaneously read from the two regions. This fact that coordinatesfrom different regions have been encountered can be interpreted, e.g.,as a particular event which may trigger actions in the controllingsoftware in the reading device or in a computer with which the devicecommunicates. Moreover, the fact that coordinates from different regionsare read simultaneously may be used to infer a more general associationor link between the two regions.

[0038] A third and a fourth aspect of the present invention shows amethod and a device, respectively, for reading a position-coding patternand an information-coding pattern on a surface. The coding patterns maycomprise symbols, which each represents at least two different valueswherein the values depend on position information and other informationfor the position-coding pattern and information-coding pattern,respectively. The method may include reading a part of the surface andstoring the information read in the form of an image. A first virtualraster of the position-coding pattern and a second virtual raster of theinformation-coding pattern are determined from the image. The firstvirtual raster and the second virtual raster contain raster points Thefirst virtual raster and the second virtual raster may be displaced inrelation to one another and may have different spatial scales.Pluralities of symbols may be located in both the position-codingpattern and the information-coding pattern. Each symbol in theposition-coding pattern may be defined by a first raster point in thefirst raster and at least one first marking and each symbol in theinformation-coding pattern may be defined by a second raster point inthe second raster and at least one second marking. The method mayfurther include determining the value of each of the symbols bydetermining a displacement of the location of the markings with respectto each respective raster point in the first and the second raster,respectively.

[0039] The position-coding pattern in the image may be separated into afirst position code for a first coordinate for the partial surface and asecond position code for a second coordinate for the partial surface bytranslating the value of each symbol into at least one first digit forthe first position code and at least one second digit for the secondposition code. The first coordinate may be calculated by means of thefirst position code and the second coordinate may be calculated by meansof the second position code.

[0040] A computer program in a reading device in pen format thatincludes a computer, for example, can implement the method.

[0041] A central part of a reading method according to the abovedescription may be to separate the different coding patterns into theinput images of a partial surface. This may be done by means ofimage-processing software in an input device, or software in a computerconnected to an input device. The image-processing software may have thecapacity to transfer image information from a spatial domain to aspatial frequency domain and to analyze the distribution of the spatialfrequencies in the input image. This frequency distribution may provideinformation about distances between frequency peaks in the frequencydomain and thus also information about each spatial resolution level,i.e. what different patterns and phase differences, i.e. rotationsbetween patterns, are found in the image. The information obtained maythen be used for determining coordinates of each of the, preferablyvirtual, raster points in the patterns and thus makes it possible todetermine the displacement of each marking in relation to the rasterpoint in the symbols which make up the pattern.

[0042] A position-coding pattern will be presented with reference toFIGS. 1, 2a-d, and 3, without being combined with another codingpattern. The purpose of this is to clarify and exemplify the principleof coding information in the form of patterns consisting of symbols.After the presentation of the position-coding pattern, a device is thenpresented in connection with FIG. 4, which can read the pattern. Afterthat, with reference to FIG. 5, it is shown how a combinedposition-coding pattern and information-coding pattern can be arrangedFIG. 6 then illustrates a distribution of spatial frequencies for aninput image of a partial surface on which two coding patterns have beenapplied. In connection with FIG. 6, it will also be discussed howreading and interpreting of a coding-patterned surface may be carriedout according to the invention.

[0043]FIG. 1 shows a part of a product in the form of a sheet of paper1, which on its surface 2 has an optically readable position-codingpattern 3, which enables position determination to be performed. Theposition-coding pattern 3 may consist of symbols 4, which aresystematically arranged over the surface 2 so that it has a “patterned”appearance. As exemplified in FIG. 1, the symbols comprise markings,which, for the sake of clarity, are round and of constant size.

[0044] The sheet of paper may have an x coordinate axis and a ycoordinate axis. In this case, position determination can be carried outon the surface of the whole product. In other cases, the surfaceprovided with a position coding pattern may consist of a smaller part ofthe product.

[0045] The position-coding pattern 3 may comprise a virtual raster,which is neither visible to the human eye nor detectable by a devicethat determines positions on the surface. The position-coding pattern 3may further comprise a plurality of symbols 4, each assuming one of fourvalues “1”-“4” as will be described in the text that follows. In FIG. 1,the position-coding pattern 3 has been greatly enlarged for the sake ofclarity. Also, only a part of the paper is shown.

[0046] The position-coding pattern 3 may be arranged so that theposition of a partial surface on the writing surface is coded by thesymbols on this partial surface. A first and a second partial surface 5a, 5 b are shown by dashed lines in FIG. 1. The part of theposition-coding pattern 3 (in this case 3×3 symbols) that is located onthe first partial surface 5 a may code a first position, and the part ofthe position-coding pattern 3 that is located on the second partialsurface 5 b may code a second position. The position-coding pattern 3may thus be partially common to the adjoining first and secondpositions. Such a position-coding pattern is designated as “floating” inthis disclosure.

[0047]FIGS. 2a-d show an embodiment of a symbol that can be used in theposition-coding pattern 3 according to the invention. The symbol may bedefined by a virtual raster point 6, which is represented by theintersection between the raster lines, and a marking 7, which may havethe form of a dot. The value of the symbol may depend on where themarking is located. In the example in FIG. 2, there are four possiblelocations, one on each of the raster lines extending from the rasterpoints 6. The displacement from the raster point 6 may be equal for allvalues. In the text that follows, the symbol has the value 1 in FIG. 2a,the value 2 in FIG. 2b, the value 3 in FIG. 2c, and the value 4 in FIG.2d. In other words, there are four different types of symbol.

[0048] thus, each symbol can represent four values “1-4”. This meansthat the position- coding pattern 3 can be divided into a first positioncode for the x coordinate, tion code for the y coordinate. The dividingis done in accordance Symbol value x code y code 1 1 1 2 0 1 3 1 0 4 0 0

[0049] Thus, the value of each symbol may be translated into a firstdigit, in this case a first the x code and a second digit, in this casesecond bit, for the y code. in this manner, two completely independentbit patterns may be obtained. The patterns can be combined into a commonpattern, which may be coded graphically with the aid of a symbolsaccording to FIG. 2.

[0050] Each position may be coded by means of a plurality of symbols. Inthis example, 4×4 symbols are used for coding a position in twodimensions, i.e. an x coordinate and a y coordinate.

[0051] The position code may be built up by means of a number series ofones and zeros where no sequence of four bits, in the number series,occurs more than once. The number series may be cyclic, which means thatno sequence of four bits, in the number series more than once if the endof the series is coupled together with its beginning. Thus, a sequenceof four bits always has an unambiguously determined position in thenumber series.

[0052] The number series can be maximally 16 bits long for a sequence offour bits to always have an unambiguously determined position in thenumber series. In this example, however, only a seven-bit-long numberseries according to the following is used:

[0053] “0 0 0 1 0 1 0”

[0054] This series contains seven unique sequences of four bits, whichcode a position in the series according to the following: Position inthis series Sequence 0 0001 1 0010 2 0101 3 1010 4 0100 5 1000 6 0000

[0055] To code the x coordinate, the number series may be writtensequentially in columms over the surface that is to be coded. The codingmay be based on the diference or position displacement between numbersin adjoining columns. The magnitude of the difference may be determinedby the position in the number series at whish the columm allowed tobegin (i.e. with which sequence). More specifically, taking thedifference modulo seven between, on the one hand, a number which iscoded by a four-bit sequence in a first column and which thus can havethe value (position) 0-6, and, on the other hand, a corresponding number(i.e. a sequence on the same “level”) in an adjoining column, may yieldthe same result independently of where along the two columns thecomparison is made. Using the difference between two columns, an xcoordinate can thus be coded which is constant for all y coordinates.

[0056] Since each position on the surface is coded with 4×4 symbols inthis example, three differences (having the value 0-6) are availableaccording to the above for coding the x coordinate. The coding may thenbe carried out in such a manner that of the three differences, one willalways have the value 1 or 2 and the other two will have the value inthe interval 3-6. Thus, no differences will be zero in the x code. Inother words, the x code may be constructed in such a manner that thedifferences will be as follows:

[0057] (3-6) (3-6) (1-2) (3-6) (3-6) (1-2) (3-6) (3-6) (3-6) (1-2) . . .

[0058] Each x coordinate may thus be coded with two numbers between 3and 6 and a subsequent number that is 1 or 2. If three is subtractedfrom the high numbers and one from the low one, a number in mixed basewill be obtained which directly provides a position in the x direction,from which the x coordinate can then be determined directly as shown inthe example below.

[0059] Using the principle described above, it is thus possible to codex coordinates 0, 1, 2 . . . by means of numbers which represent threedifferences. These differences may be coded with a bit pattern that isbased on the above number series. Finally, the bit pattern can be codedgraphically with the aid of the symbols in FIG. 2.

[0060] In many cases, when reading 4×4 symbols it may not be possible toget a complete number which codes the x coordinate but parts of twonumbers. Since the least significant part of the numbers is always 1 or2, however, a complete number can be reconstructed in a simple manner.

[0061] The y coordinates may be coded in accordance with the sameprinciple as used for the x coordinates. The cyclic number series may bewritten repeatedly in horizontal rows over the surface that is to beposition-coded. Exactly as in the case of the x coordinates, the rowsmay be allowed to begin at different positions, i.e. with differentsequences, in the number series. However, it may not be the differencesthat are used for the y coordinates, but the coordinates may be codedwith numbers which are based on the starting position of the numberseries in each row. When the x coordinate for 4×4 symbols has beendetermined, it is, in fact, possible to determine the starting positionin the number series for the rows that are included in the y code in the4×4 symbols. In the y code, the most significant digit may be determinedby allowing this to be the only one that has a value in a specificinterval. In this example, one row of four is allowed to begin atposition 0-1 in the number series to indicate that this row relates tothe least significant digit in a y coordinate, and the other three beginat positions 2-6. In the y direction, there is thus a series of numbersas follows:

[0062] (2-6) (2-6) (2-6) (0-1) (2-6) (2-6) (2-6) (0-1) (2-6) . . .

[0063] Each y coordinate may be thus coded with three numbers between 2and 6 and a subsequent number between 0 and 1.

[0064] If 0 is subtracted from the low number and 2 from the high ones,a position in the y direction in mixed base may be obtained, in the samemanner as for the x direction, from which the y coordinate can bedetermined directly.

[0065] With the above method, it is possible to code 4×4×2=32 positionsin the x direction. Each such position may correspond to threedifferences, giving 3×32=96 positions. Furthermore, it is possible tocode 5×5×5×2=250 positions in the y direction. Each such position maycorrespond to 4 rows, giving 4×250=1000 positions. Together, it is thuspossible to code 96000 positions. Since the x coding may be based ondifferences it is, however, possible to select the position at which thefirst number series begins. Taking into consideration that this firstnumber series can begin at seven different positions, it is possible tocode 7×96000=672000 positions. The starting position of the first numberseries in the first column can be calculated when the x coordinate hasbeen determined. The above-mentioned seven different starting positionsof the first series can code different sheets or writing surfaces on aproduct.

[0066] To further illustrate the invention according to this embodiment,a specific example follows here which is based on the embodiment of theposition code described.

[0067]FIG. 3 shows an example of an image with 4×4 symbols that may beread by a device for position determination.

[0068] These 4×4 symbols have the following values: 4442 3234 4424 1324

[0069] These values represent the following binary x and y codes: xcode: y code: 0000 0001 1010 0100 0000 0010 1100 1010

[0070] The vertical x sequences code the following positions in thenumber series: 2, 0, 4, and 6. The differences between the columns willbe −2 4 2, which modulo 7 gives 5, 4, 2, which, in mixed base codesposition (5-3)×8+(4-3)×2+(2-1)=16+2+1=19. Since the first coded xposition is position 0, the difference which lies in the interval 1-2and which appears in the 4×4 symbols is the twentieth such difference.Since, furthermore, there are a total of three columns for each suchdifference and there is a start column, the farthest vertical sequenceto the right in the 4×4 x code belongs to the 61st column in the x code(3×20+1=61) and that farthest to the left belongs to the 58th.

[0071] The horizontal y sequences code the following positions in thenumber series: 0, 4, 1, and 3. Since these series begin in the 58thcolumn, the starting position of the rows are these numbers minus 57modulo 7, providing the starting positions 6, 3, 0, 2. Translated intodigits in the mixed base, this becomes 6-2, 3-2, 0-0, 2-2=4 1 0 0, wherethe third digit is the least significant digit in the number inquestion. The fourth digit is then the most significant digit in thenext number. In this case, it must be the same as in the number inquestion. (The exception is when the number is question consists of thehighest possible digits in all positions. It is then apparent that thebeginning of the next number is one greater than the beginning of thenumber in question).

[0072] The position of the four-digit number becomes0×50+4×10+1×2+0×1=42 in the mixed base.

[0073] The third row in the y code is thus the 43rd which has startingposition 0 or 1, and since there are four rows in total in each suchrow, the third row is number 43×4=172.

[0074] Thus, in this example, the position of the top left-hand cornerfor the 4×4 symbol group is (58,170).

[0075] Since the x sequences in the 4×4 group begin in row 170, the xcolumns of the entire pattern begin at positions ((2 0 4 6) -169) modulo7=1 6 3 5 of the number series. Between the last starting position (5)and the first starting position, the numbers 0-19 are coded in mixedbase and by adding together the representations for numbers 0-19 inmixed base, the total difference between these columns is obtained. Aprimitive algorithm for doing this is to generate these twenty numbersand directly add together their digits. The sum obtained is called s.The sheet of paper or writing surface is then given by (5-s) modulo 7.

[0076] In the example above, an embodiment has been described in whicheach position is coded with 4×4 symbols and a number series with 7 bitsis used. Naturally, this is only an example. Positions can be coded withmore or fewer symbols. The number of symbols does not need to be thesame in both directions. The number series can have different lengthsand do not need to be binary but may be built on another base. Differentnumber series can be used for coding in the x direction and coding inthe y direction. The symbols can have different numbers of values.

[0077] In the example above, furthermore, the marking is a dot.Naturally, it can have a different appearance. For example, it mayconsist of a polygon or other shape.

[0078] In the example above, the symbols are used within a squarepartial surface for coding a position. The partial surface can haveanother form, for example hexagonal or other shape. Neither do thesymbols need to be arranged in rows and columns at an angle of 90degrees with respect to one another but can also be arranged in otherconfigurations.

[0079] Depending on the details of the embodiment, for the position codeto be detectable, the virtual raster must be determined. In the case ofonly one pattern, this can be done by studying the distance betweendifferent markings. The shortest distance found between two markingsmust originate from two adjoining symbols having the value 1 and 3 sothat the markings are located on the same raster line between two rasterpoints. When such a pair of markings has been detected, the associatedraster points can be determined with knowledge of the distance betweenthe raster points and the displacement of the markings from the rasterpoints. Once two raster points have been located, further raster pointscan be determined by means of measured distances to other markings andwith knowledge of the relative distances of the raster points. With twoor more superimposed coding patterns, the process of identifying thepatterns is somewhat different, as will be described in greater detailbelow in connection with FIGS. 5 and 6.

[0080] An embodiment of an exemplary device for position determinationis shown schematically in FIG. 4. It may include a casing 11, which mayhave the approximate format of a pen. In a short end of the casing,there may be an opening 12. The short end may bear against or may beheld at a short distance from the surface from which information isfetched.

[0081] The casing may be configured to accommodate an optical part, anelectronic part, and a power supply.

[0082] The optical part may include at least one light-emitting diode 13for illuminating the surface to be imaged and a light-sensitive areasensor 14, for example a CCD or CMOS sensor for registering atwo-dimensional image. The device may also contain a lens system.

[0083] The power supply for the device may be obtained from a battery15, which may be mounted in a separate compartment in the casing.

[0084] The electronic part may include an image-processing means 16 fordetermining a position on the basis of the image registered by thesensor 14 and, more specifically, a processor unit with a processorprogrammed for reading images from the sensor and carrying out positiondetermination and information decoding on the basis of these images.

[0085] In this embodiment, the device may also comprise a pen point 17for writing normal pigment-based writing on the surface on which theposition determination is to be carried out. The pen point 17 can beretracted and extended so that the user can control whether it is to beused. In certain applications, the device does not need to have any penpoint at all, or may employ some other marking implementation.

[0086] The device may also include buttons 18, for actuating andcontrolling the device. It may also have a transceiver 19 for wirelesstransmission, e.g. by means of IR light or radio waves, of informationto and from the device. The device can also include a display 20 forshowing positions or registered information.

[0087] Applicant's International Patent Application WO 98/20446describes a device for registering text. This device can be used forposition determination and information reading/decoding if it isprogrammed in a suitable manner. If it is to be used for pigment-basedwriting, it may also have a pen point.

[0088] The device can be divided into different physical casings, afirst casing containing components which are necessary for obtainingimages of the coding pattern and for transferring them to componentswhich are located in a second casing and which carry out thecalculations on the basis of the registered image or images.

[0089] As mentioned, calculations may be carried out by a processor thatmay use software for locating and decoding the symbols in an image andfor determining the positions from the codes thus obtained. On the basisof the above example, a person of ordinary skill in the art can designsoftware that carries out position determination on the basis of animage of a part of a position-coding pattern.

[0090] In the above embodiment, the pattern is optically readable andthe sensor is thus optical. As mentioned, the pattern can be based on aparameter other than an optical parameter. In such a case, naturally,the sensor must be of the type that can read the parameter in question.

[0091] In the above embodiment, the raster is a grid network. It canalso have other forms.

[0092] In the embodiment above, it is not the longest possible cyclicnumber series that is used. This provides a certain redundancy, whichcan be used, for example, for checking the rotation of the group ofsymbols read.

[0093]FIG. 5 shows a position-coding pattern combined with aninformation-coding pattern. The position-coding pattern in FIG. 5includes a number of symbols of which markings 502 are shown togetherwith a first raster defined by a number of raster lines 501. Theinformation-coding pattern in FIG. 5 also includes a number of symbols,of which markings 504 are shown together with a second raster comprisinga number of raster lines 503. Both patterns are of the same type as theposition-coding pattern described in detail above, therefore, nodetailed description will be given on how information is coded by meansof the location of the markings with respect to each respective raster.Note, however, that the markings 502, 504 are not located along theraster lines as in the example described above. Rather, the markings502, 504 are located in the respective quadrant defined by theintersections of the raster lines.

[0094] As has been discussed above, both coding patterns may in factencode position information. In such a case the first position-codingpattern may encode positions from a first region or area and the secondposition-coding pattern may encode positions from a second region orarea, thus increasing the total size of the region available for use.

[0095] As mentioned above, the raster lines 501, 503 can be virtualones, i.e. invisible on the product on which the pattern is applied. Theraster lines in FIG. 5 are thus shown only to increase clarity. As usedthroughout this disclosure, the term “raster” is collectively used torefer to both virtual and non-virtual rasters.

[0096] The first and second raster with raster lines 502, 504 have afirst spatial scale 505 and a second spatial scale 506 respectively andmay be displaced with respect to one another by a displacement distance507. The patterns in FIG. 5, like the above illustrations, have beenexaggerated in scale to increase clarity in these illustrations.

[0097] The different coding patterns can be displaced in relation to oneanother by a more or less optional distance and can be of differentspatial scales. The result is that the different patterns do notcoincide with one another. It is preferred that the displacement betweenthe first and the second raster, the distance between the raster pointsin the first raster and the distance between the raster points in thesecond raster are related such that interference effects are avoided.For example, the distances may not have a common integer denominatorwhich is greater than one. A product can be provided with a plurality ofdifferent coding patterns, for example three, in which the mutualdisplacements between the patterns differ from one another. Such apatterned product can also be provided with patterns with an informationdensity that is only limited by the nature of the surface of the productand the printing technique used for the application.

[0098] The coding patterns may of course be applied to the product atdifferent instances in time. For example, a product may be provided forsale having only a first position-coding pattern applied on its surface.A user of the product may subsequently apply, i.e. print, a secondcoding pattern on the product, and thereby may provide the product withfurther encoded information. Products, e.g. sheets of paper, may becompletely covered by a first coding pattern with a very highresolution. A user subsequently may apply, by using, for example, a moreor less conventional laser printer, a second coding pattern on at leasta part of the area already provided with the first coding pattern. Thissecond coding pattern may have a lower resolution as compared with thefirst pattern, depending on the capability of the specific printer used,although the pattern may encode user specific information.

[0099] Although it has been described above that the two, or more,coding patterns are similar in all but scale, the two coding patternsmay differ in other respects. For example, one of the coding patternsmay comprise markings of different sizes where the variation in sizeholds the information of the pattern. It may be possible to use anycombination of coding patterns known in the art within the scope of thepresent invention.

[0100] A method for reading and interpreting a patterned surfaceaccording to FIG. 5 will now be described with reference to FIG. 6. Themethod can be implemented in an input device such as the devicedescribed in connection with FIG. 4.

[0101] In a first step, a patterned surface may be read and an image ofthe pattern stored in an image memory. The image thus may only comprisea dot pattern without the raster lines that are indicated in FIG. 5. Inthis image, the center for each dot may then be determined in somesense, for example in the form of peak blackening or the like, and maybe described as a spike-shaped maximum at this point.

[0102] An analytic two-dimensional Fourier transformation may then becarried out on the data set, which consists of a number of spike-shapedmaxima. This operation provides a two-dimensional spectrum of spatialfrequencies. FIG. 6 illustrates such a spectrum along a spatialfrequency axis S where two peaks 601, 602 for two spatial frequenciesS1, S2 are shown. A power axis P is shown but without any marked scalesince the figure is only intended to illustrate the spectrum inqualitative terms. The peaks originate from the typical spatial distancebetween markings 502 in the position-coding pattern and, respectively,the typical spatial distance between markings 504 in theinformation-coding pattern. From a two-dimensional image of a spatialspectrum (not illustrated), it should be possible to read off the phasedifferences between the peaks, these phase differences representing therotation of the patterns.

[0103] These values, i.e. the typical spatial distance and rotationsshow the nature of the two patterns in terms of around which coordinatesthe actual dots are displaced.

[0104] After that, the calculation of positions and decoding of otherinformation from the two patterns may be carried out as described above.

[0105] Concurrently filed with the application for this patent areapplications entitled Systems and Methods for Information Storage basedon Swedish Application No. 0000947-2, filed Mar. 21, 2000, and U.S.Provisional Application No. 60/207,839, filed May 30, 2000; SecuredAccess Using a Coordinate System based on Swedish Application No.0000942-3, filed Mar. 21, 2000, and U.S. Provisional Application No.60/207,850 filed on May 30, 2000; System and Method for Printing byUsing a Position Coding Pattern based on Swedish Application No.0001245-0, filed on Apr. 5, 2000, and U.S. Provisional Application No.60/210,651, filed on Jun. 9, 2000; Apparatus and Methods Relating toImage Coding based on Swedish Application No. 0000950-6, filed on Mar.21, 2000, and U.S. Provisional Application No. 60/207,838, filed on May30, 2000; Apparatus and Methods for Determining Spatial Orientationbased on Swedish Application No. 0000951-4, filed on Mar. 21, 2000, andU.S. Provisional Application No. 60/207,844, filed on May 30, 2000;System and Method for Determining Positional Information based onSwedish Application No. 0000949-8, filed Mar. 21, 2000, and U.S.Provisional Application No. 60/207,885, filed on May 30, 2000; Methodand System for Transferring and Displaying Graphical Objects based onSwedish Application No. 0000941-5, filed Mar. 21, 2000, and U.S.Provisional Application No. 60/208,165, filed May 31, 2000; OnlineGraphical Message Service based on Swedish Application No. 0000944-9,filed Mar. 21, 2000, and U.S. Provisional Application No. 60/207,881,filed May 30, 2000; Method and System for Digitizing Freehand GraphicsWith User-Selected Properties based on Swedish Application No.0000945-6, filed Mar. 21, 2000, U.S. Provisional Application No.60/207,882, filed May 30, 2000; Data Form Having a Position-CodingPattern Detectable by an Optical Sensor based on Swedish Application No.0001236-9, filed Apr. 5, 2000, and U.S. Provisional Application No.60/208,167, filed May 31, 2000; Method and Apparatus for ManagingValuable Documents based on Swedish Application No. 0001252-6, filedApr. 5, 2000, and U.S. Provisional Application No. 60/210,653 filed Jun.9, 2000; Method and Apparatus for Information Management based onSwedish Application No. 0001253-4 filed Apr. 5, 2000, and U.S.Provisional Application No. 60/210,652, filed Jun. 9, 2000; Device andMethod for Communication based on Swedish Application No. 0000940-7,filed Mar. 21, 2000, and U.S. Provisional Application No. 60/208,166,filed May 31, 2000; Information-Related Devices and Methods based onSwedish Application No. 0001235-1, filed Apr 5, 2000, and U.S.Provisional Application No. 60/210,647, filed Jun. 9, 2000; Processingof Documents based on Swedish Application No. 0000954-8, filed Mar. 21,2000, and U.S. Provisional Application No. 60/207,849, filed May 30,2000; Secure Signature Checking System based on Swedish Application No.0000943-1, filed Mar. 21, 2000, and U.S. Provisional Application No.60/207,880, filed May 30, 2000; Identification of Virtual RasterPattern, based on Swedish Application No. 0001235-1, filed Apr. 5, 2000,and U.S. Provisional Application No. 60/210,647, filed Jun. 9, 2000, andSwedish Application No. 0004132-7, filed Nov. 10, 2000, and U.S.Provisional Application No.______, filed Jan. 12, 2001; and a new U.S.Provisional Application entitled Communications Services Methods andSystems.

[0106] The technical disclosures of each of the above-listed U.S.applications, U.S. provisional applications, and Swedish applicationsare hereby incorporated herein by reference. As used herein, theincorporation of a “technical disclosure” excludes incorporation ofinformation characterizing the related art, or characterizing advantagesor objects of this invention over the related art.

[0107] In the foregoing Description of Preferred Embodiments, variousfeatures of the invention are grouped together in a single embodimentfor purposes of streamlining the disclosure. This method of disclosureis not to be interpreted as reflecting an intention that the claimedinvention requires more features than are expressly recited in eachclaim. Rather, as the following claims reflect, inventive aspects lie inless than all features of a single foregoing disclosed embodiment. Thus,the following claims are hereby incorporated into this Description ofthe Preferred Embodiments, with each claim standing on its own as aseparate preferred embodiment of the invention.

What is claimed is:
 1. A surface, comprising: a first coding pattern ofsymbols and a second coding pattern of symbols wherein: each symbol ofthe first coding pattern has at least two different values; each symbolof the second coding pattern has at least two different values; eachsymbol of the first coding pattern is defined by a first raster pointand at least one first marking, wherein the first raster point isincluded in a first raster which extends over the surface; and eachsymbol of the second coding pattern is defined by a second raster pointand at least one second marking, wherein the second raster point isincluded in a second raster which is displaced in relation to the firstraster and has a different spatial scale than the first raster.
 2. Asurface according to claim 1, wherein a value of each symbol of thefirst and the second coding patterns is based on a location of the firstand second marking in relation to the first and second raster point inthe first and second raster, respectively.
 3. A surface according toclaim 2, wherein a displacement between the first and the second raster,a distance between the raster points in the first raster, and a distancebetween the raster points in the second raster are such thatinterference effects are avoided.
 4. A surface according to claim 1,wherein the first and second markings of the symbols of the first andsecond coding pattern are identical.
 5. A surface according to claim 1,wherein: the first coding pattern is a position-coding pattern, whichcodes a plurality of positions on the surface, wherein each position onthe surface is coded by a plurality of symbols; and the second codingpattern is an information-coding pattern, which codes other information.6. A surface according to claim 5, wherein each symbol of the firstcoding pattern contributes to the coding of more than one of saidplurality of positions on the surface.
 7. A surface according to claim5, wherein each symbol of the first coding pattern contributes to codinga first and a second position coordinate.
 8. A surface according toclaim 7, wherein a value of each symbol of the first coding pattern canbe translated into at least one first digit which is used for coding thefirst position coordinate and at least one second digit which is usedfor coding the second position coordinate, wherein the symbols in thefirst coding pattern together represent a first position code for thefirst position coordinate and a second position code for the secondposition coordinate.
 9. A surface according to claim 5, wherein thefirst coding pattern is based on a first cyclic number series wherein nosequence with a first predetermined number of digits in the first cyclicnumber series occurs more than once.
 10. A surface according to claim 9,wherein the first position coordinate is coded based on the first cyclicnumber series being repeated in columns over the surface and wherein thecolumns begin at different places in the first cyclic number series. 11.A surface according to claim 10, wherein the second position coordinateis coded with a second cyclic number series being repeated in rows overthe surface, the rows beginning at different places in the second cyclicnumber series, and wherein no sequence with a second predeterminednumber of digits in the second cyclic number series occurs more thanonce.
 12. A surface according to claim 11 further comprising: aplurality of writing surfaces wherein each writing surface includes thefirst coding pattern, wherein the first coding pattern of eachrespective writing surface differs for the different writing surfacesthrough the sequence in the cyclic number series with which apredetermined column or row begins.
 13. A surface according to claim 1,wherein the first coding pattern and the second coding pattern areposition-coding patterns.
 14. A surface according to claim 1, whereinthe first and the second raster and the first and second raster pointsare virtual.
 15. A surface according to claim 1, wherein each symbol inthe first and the second coding pattern has only one marking, which canbe placed on one of four predetermined positions on lines of the firstand second raster, respectively, so that each symbol has one of onlyfour values.
 16. A surface according to claim 1, wherein the first andsecond coding patterns are optically readable.
 17. A method forproducing a position-coding pattern and an information-coding pattern ona surface, wherein the coding patterns comprise symbols, each of whichrepresents at least two different values, wherein the values depend onposition information and other information for the position-codingpattern and the information-coding pattern, respectively, the methodcomprising: determining a first raster with first raster points and asecond raster with second raster points, wherein the second raster isdisplaced in relation to the first raster and has a different spatialscale than the first raster; determining a configuration of the symbolsof the position-coding pattern and the information-coding pattern,wherein each symbol of the position-coding pattern is defined by a firstraster point in the first raster and at least one first marking and eachsymbol in the second coding pattern is defined by a second raster pointin the second raster and at least one second marking.
 18. A methodaccording to claim 17, wherein determining a configuration of thesymbols includes displacing the markings in relation to each firstraster point and second raster point, respectively based on the value ofa symbol of the position-coding pattern and the information-codingpattern, respectively.
 19. A method according to claim 18, whereindetermining a first raster and a second raster includes determining adisplacement between the first and the second raster, a distance betweenthe first raster points in the first raster, and a distance between thesecond raster points in the second raster such that interference effectsare avoided.
 20. A method according to claim 17, wherein theposition-coding pattern codes a plurality of positions on the surfaceand each position is coded by a plurality of symbols.
 21. A methodaccording to claim 20, wherein each symbol in the position-codingpattern contributes to the coding of more than one of said plurality ofpositions.
 22. A method according to claim 20, wherein each symbol inthe position-coding pattern contributes to the coding of a first and asecond position coordinate.
 23. A method according to claim 22, whereinthe value of each symbol in the position-coding pattern can betranslated into at least one first digit which is used for coding thefirst position coordinate and at least one second digit which is usedfor coding the second position coordinate, wherein the symbols in theposition-coding pattern together represent a first position code for thefirst position coordinate and a second position code for the secondposition coordinate.
 24. A method according to claim 20, wherein theposition-coding pattern is based on a first cyclic number series whereinno sequence with a first predetermined number of digits in the firstcyclic number series occurs more than once.
 25. A method according toclaim 22, wherein the first coordinate is coded based on a first cyclicnumber series being repeated in columns over the surface, the columnsbeginning at different places in the first cyclic number series, andwherein no sequence with a first predetermined number of digits occursmore than once in the first cyclic number series.
 26. A method accordingto claim 25, wherein the second coordinate is coded based on a secondcyclic number series being repeated in rows over the surface, the rowsbeginning at different places in the second cyclic number series, andwherein no sequence with a second predetermined number of digits occursmore than once in the second cyclic number series.
 27. A methodaccording to claim 26 further comprising: determining a coding patternfor a plurality of writing surfaces wherein each writing surfaceincludes the position-coding pattern, wherein the position-codingpattern of each respective writing surface differs for the differentwriting surfaces through the sequence in the cyclic number series withwhich a predetermined column or row begins.
 28. A method according toclaim 17, wherein the first and second raster and the first and secondraster points are virtual.
 29. A method according to claim 17, whereinproducing the information-coding pattern includes producing a secondposition-coding pattern having symbols that represent positions.
 30. Amethod according to claim 17, wherein each symbol in the position-codingpattern and the information-coding pattern has only one marking whichcan be placed in one of four predetermined positions on lines of thefirst and second raster, respectively, so that each symbol has one ofonly four values.
 31. A method according to claim 17, wherein theinformation coding pattern is produced subsequent to the production ofthe position coding pattern.
 32. A computer program which comprisesinstructions for causing a computer to execute a method according toclaim
 17. 33. A method for reading a position-coding pattern and aninformation-coding pattern on a surface, wherein the coding patternsinclude symbols each of which represents at least two different values,wherein the values depend on position information and other informationfor the position-coding pattern and information-coding pattern,respectively, the method comprising: reading a part of the surface andstoring the read information in an image; determining a first virtualraster with raster points in the image associated with theposition-coding pattern and a second virtual raster with raster pointsin the image associated with the information-coding pattern, wherein thesecond raster is displaced in relation to the first raster and has aspatial scale different from a special scale of the first raster;locating a plurality of symbols in the position-coding pattern andinformation-coding pattern; determining a value of each of the pluralityof symbols, wherein each symbol of the position-coding pattern isdefined by a first raster point in the first virtual raster and at leastone first marking, and each symbol of the information-coding pattern isdefined by a second raster point in the second raster and at least onesecond marking; separating the position-coding pattern in the image intoa first position code for a first coordinate for a partial surface and asecond position code for a second coordinate for the partial surface bytranslating the value of each symbol into at least one first digit forthe first position code and at least one second digit for the secondposition code; and calculating the first coordinate using the firstposition code and the second coordinate using the second position code.34. A method according to claim 33, wherein determining the value ofeach of the plurality of symbols of the position-coding pattern and aninformation-coding pattern include determining a displacement of thelocation of the markings for each symbol in relation to the first andsecond raster point for each symbol, respectively.
 35. A methodaccording to claim 34, wherein determining the first and second rastersis carried out using a spatial frequency spectrum of the image.
 36. Amethod according to claim 35, wherein the spatial frequency spectrum isdetermined by Fourier transformation.
 37. A computer program whichcomprises instructions for causing a computer to execute a methodaccording to claim
 33. 38. A computer program which comprisesinstructions for causing a computer to execute a method according to anyone of claims
 33. 39. A method according to claim 33, furthercomprising: separating the information-coding pattern in the image intoa third position code for a third coordinate for a partial surface and afourth position code for a fourth coordinate for a partial surface bytranslating the value of each symbol into at least a third digit for athird position code and at least a fourth digit for a fourth positioncode; and calculating the third coordinate based on the third positioncode and the fourth coordinate based on the fourth position code;wherein the symbols of the information -coding pattern representpositions.
 40. A device for reading a position-coding pattern and aninformation-coding pattern on a surface, wherein the position-codingpattern and the information-coding pattern comprise symbols, each ofwhich represents at least two different values, wherein the valuesdepend on position information and other information for theposition-coding pattern and the information-coding pattern,respectively, the device comprising: means for reading a part of thesurface and storing information read in an image; means for determininga first virtual raster with first raster points in the image associatedwith the position-coding pattern and a second virtual raster with secondraster points in the image associated with the information-codingpattern, wherein the second raster is displaced in relation to the firstraster and has a spatial scale different from a spatial scale of thefirst raster; means for locating a plurality of symbols in theposition-coding pattern and information-coding pattern; means fordetermining a value of each of said plurality of symbols, wherein eachsymbol in the position-coding pattern is defined by a first raster pointin the first raster and at least one first marking and each symbol inthe information-coding pattern is defined by a second raster point inthe second raster and at least one second marking; means for separatingthe position-coding pattern in the image into a first position code fora first coordinate for a partial surface and a second position code fora second coordinate for the partial surface by translating the value ofeach symbol into at least a first digit for a first position code and atleast a second digit for a second position code; and means forcalculating the first coordinate based on the first position code andthe second coordinate based on the second position code.
 41. A deviceaccording to claim 40, wherein the means for determining the value ofeach of the plurality of symbols of the position-coding pattern and theinformation-coding pattern includes means for determining a displacementof the location of the markings for each symbol in relation to the firstraster point and the second raster point respectively for each symbol,respectively.
 42. A device according to claim 41, wherein the means fordetermining a first virtual raster and a second virtual raster areexecuted with the aid of means for determining a spatial frequencyspectrum of the image.
 43. A device according to claim 42, wherein thespatial frequency spectrum is determined using a Fourier transformation.44. A device according to claim 40, further comprising: means forseparating the information-coding pattern in the image into a thirdposition code for a third coordinate for a partial surface and a fourthposition code for a fourth coordinate for a partial surface bytranslating the value of each symbol into at least a third digit for athird position code and at least a fourth digit for a fourth positioncode; and means for calculating the third coordinate based on the thirdposition code and the fourth coordinate based on the fourth positioncode; wherein the symbols of the information -coding pattern representpositions.
 45. A device according to claim 40, where in the device ishandheld.
 46. A device according to claim 40, wherein the deviceincludes means for wireless transmission of information.